1. Field of the Invention
The invention relates to a color image forming apparatus in which a toner on an intermediate transfer member having a predetermined range of loss tangent is removed by a blade member.
2. Related Background Art
In recent years, even in a color image forming apparatus using an electrophotographic process, it has been required to cope with various recording media. Therefore, use is widely made of a color image forming apparatus using an intermediate transfer member capable of coping with various recording media.
Heretofore, as an intermediate transfer member, use has been widely made of one of a single-layer construction of polyimide resin.
However, when a toner image borne on a photosensitive member is transferred to the intermediate transfer member of a single-layer construction of polyimide resin, there occurs so-called scattering in which the outline of the toner image on the intermediate transfer member becomes blurred. When the toner image on the image bearing member is being transferred, the intermediate transfer belt contacts with the image bearing member. At this time, in the outline portion of the toner image on the image bearing member, a gap is caused between the intermediate transfer member and the image bearing member by the thickness of the toner image. Due to the presence of this gap, scattering occurs.
So, an intermediate transfer member using an elastic material such as rubber has come to be used.
The intermediate transfer member using an elastic material is quickly deformed in conformity with the thickness of the toner image. In the outline portion of the toner image on the photosensitive member, no gap is caused between the intermediate transfer member and the photosensitive member. In this manner, the occurrence of the scattering is suppressed.
Here, the loss tangent (tan δ) is an index indicative of the magnitude of a force which a substance absorbs when deformed, on the basis of the time from after a force has been imparted to the substance until the substance is deformed and is further restored to its original shape.
The greater is the loss tangent (tan δ), the longer becomes the time required from after a force has been imparted to the substance until the substance is deformed.
Conversely, the smaller is the loss tangent (tan δ), the shorter becomes the time from after a force has been imparted to the substance until the substance is deformed. Also, it becomes difficult for the imparted force to be absorbed.
Now, as means for removing any toner residual on the intermediate transfer member after the toner image on the intermediate transfer member has been transferred to a recording medium, use is widely made of a blade member of which the edge contacts with the intermediate transfer member. This is because of its simple construction.
However, when the blade member was used as the means for removing the toner residual on the intermediate transfer member using an elastic material such as rubber, there occurred so-called faulty cleaning in which the residual toner is not removed.